This invention relates to the satisfaction of the sweet tooth. Specifically, it relates to a radical new way of producing high-quality refined cane sugar from raw cane sugar. However, to fully understand its significance, it is necessary to understand some basic information about what cane sugar is and how it has heretofore been mass-produced.
Cane sugar is a name commonly used to refer to crystalline sucrose, a dissacharide compound used throughout the world in food-processing applications as a sweetener. Crystalline sucrose is primarily produced from the sugarcane plant, a plant which is cultivated in the tropical and semitropical regions of the earth.
Throughout the world today, production of refined cane sugar from sugarcane has been accomplished in two steps: (a) the raw sugar process; and (b) the refinery process. In the raw sugar process, sugar mills, located in or near the cane fields, convert the harvested sugarcane plant into a commodity of international commerce known as raw sugar. The raw sugar is transported to sugar refineries, located in population centers throughout the world, where it is converted into its various refined end products. In contrast to the sugar mill, almost the entire output of the sugar refinery is intended, in one form or another, for human consumption.
It should be noted that there have historically been a few classes of unrefined sugar which are intended for human consumption, although they account for but a small proportion of the sugar consumed. One example is whole sugar, a sugar product made by boiling down the cane juice extracted from the sugarcane plant, without the elimination of any impurities. The mixture solidifies upon cooling and is ground resulting in a dark-brown rock-hard sugar product known as jaggery, panela, or muscovado.
Another crude sugar product is plantation white. This product is a bit more visually attractive, but it is only slightly more refined than whole sugar. Basically, plantation white is made directly from the sugarcane plant without going through the raw sugar stage. It is generally a local product of sugar mills, sold at a discounted price, because, although it is perfectly edible, it is not nearly as pure as refined sugar and it cannot be stored for as long.
In the production of raw sugar in the sugar mill, the sugarcane stalks are chopped into small pieces. Then, cane juice is extracted from the sugarcane, leaving behind a fibrous material called bagasse. The extracted juice is then clarified, in part by settling and in part by the addition of heat and lime, which induces precipitation of a floc which, upon removal, enhances the clarification. In many sugar mills, sulfur dioxide is bubbled through the juice, resulting in a bleaching effect which yields a lighter-colored raw sugar. The clarified juice is then processed through a series of evaporators to eliminate water, which is approximately 85% of the cane juice, resulting in a concentrated sugar solution called syrup. The syrup is then put through a crystallization process, which generates sugar crystals and further separates impurities. Finally, centrifugation separates raw sugar from the syrup, now termed molasses. The molasses is usually processed more than once so that as much of the sugar as possible can be recovered from the syrup.
In the sugar refinery, the raw sugar is cleaned and then melted, producing a refinable liquid termed the sugar liquor (or, simply, the liquor). Then, the liquor is clarified to remove precipitates and other particulate matter. In anticipation of the clarification process, it is commonplace to add substances such as lime which coagulate some of the impurities and form precipitates, as in the raw sugar manufacturing process. Then, the liquor is filtered to remove the precipitates. Typically, the decolorization step which follows is accomplished by carbon adsorbents, such as bone char or activated carbon. In a majority of cases, sulphur dioxide is used to still further improve (bleach) the visual appearance of the resulting sugar. Although carbon adsorbents remain the principal method of decolorization, it should be noted that, because many colorants are of an anionic character, some refineries have chosen to use ion exchange units for color removal. At this point, the liquor is crystal clear with no turbidity. The liquor is passed through evaporators to remove the water and the remaining product is then passed to a vacuum pan for further evaporation and crystallization. A vacuum pan is basically an evaporator which allows for the evaporation of water at a reduced temperature, so that there is less thermal destruction of the sucrose. The end product is then passed through centrifuges to separate the white crystals from the liquor, now termed a syrup.
This basic process, raw sugar manufacturing followed by raw sugar refining, is the process commonly used throughout the world today to produce high-quality white refined cane sugar with a polarization (or, optically measured purity) of from about 99.40% to about 99.99%. It is a two-step process which is employed even in locations where there is a sugar refinery near, or even within, a sugar mill. Even entities outside the sugar industry have arranged their business affairs to accommodate this state of the technology. Raw sugar is traded worldwide as a commodity on the New York and London stock exchanges.
Thus, heretofore, the sugar mills have produced crude sugar products, their main product being raw sugar. The high-quality refined sugars demanded in major population centers, however, have come from another source: the sugar refinery. The sugar refinery is a technologically sophisticated operation that employs expensive equipment and numerous chemicals in order to produce the refined sugar product.
The invention now makes it possible for the sugar refinery to produce high quality refined sugar according to an entirely new and superior method. The inventive process features numerous advantages as disclosed below, among them being the elimination of the need for many of the expensive and hazardous chemicals presently employed in these refineries (e.g. chemicals used to "bleach" the liquor through such processes as clarification with phosphoric acid, decolorization by phosphate-lime treatment or activated carbon). Thus, the invention benefits the U.S. public generally in that it minimizes, at the source, chemicals which are frequent contributors to environmental pollution.